In general, thermoelectric modules are used in thermoelectric power generation systems based on a Seebeck effect that electromotive force is generated using the difference in temperature between both surfaces of the thermoelectric modules.
When thermoelectric generation is performed by the thermoelectric module, as the difference in temperature between a heat absorption part and a heat radiation part is greatly maintained, the quantity of power generated through the thermoelectric generation may be increased. In this case, a heat transfer rate from a heat source to the thermoelectric module greatly influences the quantity of power generated from the thermoelectric generation.
In the thermoelectric module, a plurality of thermoelectric pellets having mutually different polarities (N type semiconductor and P type semiconductor) are alternately aligned with each other, and electrically connected with each other in series by electrodes, and an insulating substrate may be attached to each electrode.
The electrodes include a first electrode, which receives high-temperature heat, corresponding to the heat absorber of the thermoelectric module, and a second electrode, which receives low-temperature heat, corresponding to the heat radiation part of the thermoelectric module. The first and second electrodes are bonded to the thermoelectric pellets, respectively, by adhesives having conductivity. However, since the first and second electrodes require mutually different use temperatures, the first electrode is bonded to the thermoelectric pellet using a first adhesive having a higher melting point, and the second electrode is bonded to the thermoelectric pellet using a second adhesive having a lower melting point.
In a conventional thermoelectric module manufacturing apparatus to manufacture the thermoelectric module, first electrodes are bonded to the thermoelectric module using the first adhesive under a higher-temperature atmosphere, and then second electrodes are bonded to the thermoelectric module using the second adhesive under a lower-temperature atmosphere.
According to the conventional thermoelectric module, the surface of the thermoelectric pellet, to which the second electrode is bonded, is oxidized due to the higher-temperature atmosphere made when the first electrode is bonded to the thermoelectric pellet. As a result, according to the conventional thermoelectric module, the wettability for the bonding of the second electrode may be adversely influenced, and electric conductivity and thermal conductivity may be degraded, and the performance or the durability of the thermoelectric module may be degraded.
In addition, according to the conventional thermoelectric module manufacturing apparatus, two bonding processes are required for the electrodes. Accordingly, the productivity of the thermoelectric module may be lowered.